Using the useCurrencies Hook

In this section, we will be looking at how to use the useCurrencies hook to retrieve a list of available cryptocurrencies and tokens. This method is essential when you need to get information on the various currencies supported by Ledger Services Kit.

Introduction to useCurrencies Hook

The useCurrencies hook is part of the @ledgerhq/wallet-api-client-react package. This hook allows you to fetch an array of supported cryptocurrencies and tokens.

Each currency object in the array contains essential information such as its type (e.g., CryptoCurrency or TokenCurrency, id, ticker, name, family, color, and decimals).

For tokens, additional properties like standard and contract are included.

Handling Large Datasets

As of the latest data, the useCurrencies hook returns an array with up to 7501 elements when unfiltered. Due to the size of this dataset, it is essential to handle this data efficiently.

You might not want to render all elements on the UI simultaneously, as it could affect the performance. Instead, you can implement pagination, virtualisation or selectively display the data based on user input.

In addition, you can filter the currencies accessible by setting the "currencies" property inside your manifest. See the families subsection for more information about currencies filtering.

Sample Code

Here is an example that shows how to use the useCurrencies hook inside a React component:

Required permission: currency.list

import React, { useState } from "react";
import { useCurrencies } from "@ledgerhq/wallet-api-client-react";
 
function App() {
  const { currencies } = useCurrencies();
  const [response, setResponse] = useState(undefined);
 
  const handleCurrencies = () => {
    setResponse(currencies?.map((currency) => <p>{currency.name}</p>));
  };
 
  return (
    <>
      <h1>Supported Currencies</h1>
      <button onClick={handleCurrencies}>Show Currencies</button>
      <div>{response}</div>
    </>
  );
}
 
export default App;

In this example:

• We import the useCurrencies hook from the @ledgerhq/wallet-api-client-react package.

• We use the hook to get the currencies array.

• We define a handleCurrencies function that updates the state with a list of currency names.

• When the button is clicked, it displays the list of supported currencies.

Understanding the Response

Here is an example of a partial response from the useCurrencies hook:

[
  {
    "type": "CryptoCurrency",
    "id": "bitcoin",
    "ticker": "BTC",
    "name": "Bitcoin",
    "family": "bitcoin",
    "color": "#ffae35",
    "decimals": 8
  },
  {
    "type": "TokenCurrency",
    "standard": "ERC20",
    "id": "ethereum/erc20/gods_unchained",
    "ticker": "GODS",
    "contract": "0xccC8cb5229B0ac8069C51fd58367Fd1e622aFD97",
    "name": "Gods Unchained",
    "parent": "ethereum",
    "color": "#0ebdcd",
    "decimals": 18
  }
]

Each object in the array represents a cryptocurrency or token and contains the following properties:

• type: Specifies whether the currency is a base cryptocurrency like Bitcoin or Ethereum (CryptoCurrency) or a token like an ERC20 token (TokenCurrency).

• id: A unique identifier for the currency.

• ticker: The ticker symbol of the currency.

• name: The full name of the currency.

• family: The blockchain family the currency belongs to, such as bitcoin or ethereum.

• color: A color code usually associated with the currency for branding.

• decimals: The number of decimals the smallest unit of this currency can be divided into.

For tokens (TokenCurrency), there are additional properties:

• standard: Indicates the token standard (onlyERC20 this is in fact a bug as multiple standards should be represented. We advise not to rely on this property for now).

• contract: The smart contract address for the token.

• parent: Specifies the parent blockchain of the token.

Keep in mind that the actual response from the useCurrencies hook might be extensive, especially if you set the "currencies" property of your manifest to "*".